This invention relates in general to a valve and more particularly to a control valve of the type known as a rotary plug valve used as a balance valve or a shut-off valve.
Valves of the general type to which the invention pertains are taught by U.S. Pat. Nos. 3,380,704; 3,314,643; 4,113,228; 3,590,473; and 4,113,228. In general valves of this type comprise a valve housing having a longitudinal bore which is connected in series in a pipe. The valve housing has a cylindrical plug or rotor member mounted therein for rotation about an axis perpendicular to the longitudinal bore. The rotor is typically of solid metal and is pierced by a passage so that fluid may flow through the pipe when the rotor is turned to a position wherein the passage is coincident with the longitudinal bore. If the rotor is turned by 90 degrees, the passage is perpendicular to the bore and fluid cannot flow.
One problem in the manufacture of such valves is that of meeting current leakage specifications.